- W David Stahlman: Department of Psychology, University of California, Los Angeles.
Recent studies have demonstrated that the expectation of reward delivery has an inverse relationship with operant behavioral variation (e.g., Stahlman, Roberts, & Blaisdell, 2010). Research thus far has largely focused on one aspect of reinforcement - the likelihood of food delivery. In two experiments with pigeons, we examined the effect of two other aspects of reinforcement: the magnitude of the reward and the temporal delay between the operant response and outcome delivery. In the first experiment, we found that a large reward magnitude resulted in reduced spatiotemporal variation in pigeons' pecking behavior. In the second experiment, we found that a 4-s delay between response-dependent trial termination and reward delivery increased variation in behavior. These results indicate that multiple dimensions of the reinforcer modulate operant response variation.